Alka Yadav

Silver nanoparticles as a new generation of antimicrobials

Silver has been in use since time immemorial in the form of metallic silver, silver nitrate, silver sulfadiazine for the treatment of burns, wounds and several bacterial infections. But due to the emergence of several antibiotics the use of these silver compounds has been declined remarkably. Nanotechnology is gaining tremendous impetus in the present century due to its capability of modulating metals into their nanosize, which drastically changes the chemical, physical and optical properties of metals. Metallic silver in the form of silver nanoparticles has made a remarkable comeback as a potential antimicrobial agent. The use of silver nanoparticles is also important, as several pathogenic bacteria have developed resistance against various antibiotics. Hence, silver nanoparticles have emerged up with diverse medical applications ranging from silver based dressings, silver coated medicinal devices, such as nanogels, nanolotions, etc.

Fabrication of silver nanoparticles by Phoma glomerata and its combined effect against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.

Aims:  We report extracellular synthesis of silver nanoparticles (Ag‐NPs) from Phoma glomerata and its efficacy against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The bacteria exhibiting resistance to various antibiotics showed remarkable sensitivity, when used in combination of antibiotics and Ag‐NPs.

Mechanistic aspects in the biogenic synthesis of extracellular metal nanoparticles by peptides, bacteria, fungi, and plants

Metal nanoparticles have been studied and applied in many areas including the biomedical, agricultural, electronic fields, etc. Several products of colloidal silver are already on the market. Research on new, eco-friendly and cheaper methods has been initiated. Biological production of metal nanoparticles has been studied by many researchers due to the convenience of the method that produces small particles stabilized by protein. However, the mechanism involved in this production has not yet been elucidated although hypothetical mechanisms have been proposed in the literature. Thus, this review discusses the various mechanisms provided for the biological synthesis of metal nanoparticles by peptides, bacteria, fungi, and plants. One thing that is clear is that the mechanistic aspects in some of the biological systems need more detailed studies.

CRC 675—Current Trends in Phytosynthesis of Metal Nanoparticles

Nanotechnology is emerging as a field of applied science and technology. Synthesis of nanoparticles is done by various physical and chemical methods but the biological system is gaining attention as an eco-friendly technique. The biosynthetic method employing plant parts is proving as a simple and cost-effective method for the synthesis of nanoparticles. The present mini review focuses on the different systems utilized for the synthesis of nanoparticles with special emphasis on the use of plants for the synthesis process, its applications and future directions.

Biofabrication of Silver Nanoparticles by Opuntia ficus-indica: In vitro Antibacterial Activity and Study of the Mechanism Involved in the Synthesis

We report Opuntia ficus-indica mediated synthesis of colloidal silver nanoparticles. Detection and characterization of nanopar- ticles were carried out by UV-Vis- and Fourier Transform Infra Red Spectroscopy, Scanning Electron Microscopy and X-ray Diffraction analysis respectively. The aim of the present study was synthesis of silver nanoparticles, assessment of their antibacterial activity, and study of possible mechanism involved. The silver nanoparticles in combination with commercially available antibiotics showed a re- markable antibacterial activity. Some of the commercially available antibiotics in combination with silver nanoparticles showed remark- able activity. However, the maximum activity was demonstrated by Ampicillin followed by Streptomycin and Vancomycin. On the basis of the information obtained in this work, two-step mechanism has been proposed as bioreduction and formation of an intermediate com- plex leading to formation of capped nanoparticles.

Fungi as an efficient mycosystem for the synthesis of metal nanoparticles: progress and key aspects of research

Nanotechnology is an emerging cutting-edge technology, which involves interdisciplinary subjects, such as physics, chemistry, biology, material science and medicine. Different methods for the synthesis of nanoparticles have been discussed here. Although physical and chemical methods have been successfully used to synthesize nanoparticles, the use of hazardous chemicals and synthesis at high temperature is a matter of concern. Hence, there is a necessity to develop eco-friendly techniques for the synthesis of nanoparticles. Biosynthesis of nanoparticles by fungi, bacteria, actinomycetes, lichen and viruses have been reported eco-friendly. Moreover, the fungal system has emerged as an efficient system for nanoparticle synthesis as fungi possess distinctive characters including high wall binding capacity, easy to culture and simpler biomass handling, etc. In this review, we have discussed fungi as an important tool for the fabrication of nanoparticles. In addition, methods and mechanism for synthesis of nanoparticles and its potential applications have also been discussed.

Myconanotechnology: a new and emerging science.

The term nanotechnology was defined by the Tokyo Science University Professor Norio Taniguchi in 1974 (Taniguchi, 1974) as the creation and exploitation of materials in the size range of 1–100nm. Nanotechnology is multidisciplinary across science and includes aspects of research and technology development in many areas of physics, chemistry and biology (McNeil, 2005; Uskokovic, 2008). Nanoparticles are metal particles smaller than 100 nm that can be synthesized in numerous shapes (e.g. spherical, triangular, rods) from various metal ions. Nanoparticles have many different applications and are used in a number of fields, including medicine, pharmacology, environmental monitoring and electronics (Liu, 2006).Myconanotechnology (myco = fungi, nanotechnology = the creation and exploitation of materials in the size range of 1–100 nm) is a new term that is proposed here for the first time. It is defined as the fabrication of nanoparticles by fungi and their subsequent application, particularly in medicine. Myconanotechnology is the interface between mycology and nanotechnology, and is an exciting new applied interdisciplinary science that may have considerable potential, partly due to the wide range and diversity of fungi.The current interest in metallic nanoparticles is due to their variable chemical, physical and optical properties, and recent developments in the field of nanostructures have ensured that nanotechnology will play a crucial role in the future development of many scientific applications. The use of nanotechnology for the synthesis of nanomaterials is a rapidly developing emerging field. Numerous protocols have been developed to synthesize nanoparticles of different shapes and sizes by physical and chemical methods (e.g. Jana

Plants as potential synthesiser of precious metal nanoparticles: progress and prospects

The synthesis of metal nanoparticles is an active area of research in the field of nanotechnology. A variety of chemical and physical methods are used for synthesis of nanoparticles. However, these methods suffer from many drawbacks including use of toxic solvents, high energy consumption, hazardous by products etc. Hence, there is an essential need to develop environment-friendly methods for synthesis of metal nanoparticles. A promising approach to overcome this need is to harness the biological sources for synthesis of metal nanoparticles. Over the past several years, plants and their different products have come up as a low-cost, energy-efficient and non-toxic approach for synthesis of metal nanoparticles. In the present review, the authors provide an overview of various reports of the synthesis of metal nanoparticles by plants, the progress and future prospects of this field.

Biogenic Nanoparticles: An Introduction to What They Are, How They Are Synthesized and Their Applications

Metal nanoparticles are well known to possess significant applications in different fields like electronics, agriculture, medicine, etc. A number of physical and chemical methods to date are available for the synthesis of nanoparticles. However, because of the drawbacks of these methods, researchers are focusing toward the development of protocols that offer use of biological agents for the synthesis of nanoparticles. Biogenic nanoparticles are safe, nontoxic, eco-friendly and toward a greener approach. In addition, biogenic nanoparticles offer applications in different fields of science and technology. But certain issues such as developing the exact mechanism for the synthesis of nanoparticles and the effect of size and shape on synthesis need to be considered. Thus, the present chapter offers an insight toward biogenic nanoparticles, their synthesis methods, and also the applications offered by biogenic nanoparticles.

Potential Role of Biological Systems in Formation of Nanoparticles: Mechanism of Synthesis and Biomedical Applications

Nanotechnology is essentially related with the synthesis of nanoparticles of varying size and shapes. With the search of envi- ronment-friendly protocols for the synthesis of nanoparticles a diverse group of biological agents have been emerged. These biological agents are safe, eco-friendly and lead to green synthesis of nanoparticles. The present review focuses on the role of biological agent(s) towards the development of green nanotechnology, the applications of nanoparticles in different fields of science and technology, and also the toxicological effects of nanoparticles.